1. Field of the Invention
The present invention relates to a dielectric capacitor, in which a first electrode and a second electrode are connected to a dielectric film, respectively, a memory and a method of manufacturing the same.
2. Description of the Related Art
A ferroelectric memory is a rapidly rewritable, non-volatile memory by means of rapid polarization inversion and its residual polarization of a ferroelectric film. Conventionally, as a ferroelectric memory, a memory in which a dielectric capacitor and a transistor are arranged in parallel to the direction along which a base surface extends is known for example. In such a ferroelectric memory, for example, the dielectric capacitor has a construction in which an adhesive layer made of titanium (Ti), a bottom electrode layer made of platinum (Pt), a ferroelectric film made of a bismuth (Bi) inclusion layer structure oxide or PZT which is a solid solution of PbTi3 and PbZrO3, and a top electrode layer made of platinum are stacked successively on a base sandwiching an insulating layer in between. It is difficult for micorfabrication to be performed on platinum, so a precious metal other than platinum can be used for the bottom electrode layer and the tope electrode layer.
Further, in order to increase information recording density, a so-called stack type capacitor in which a transistor and a ferroelectric capacitor are placed so as to be stacked on the base is known. In the ferroelectric memory, for example, the transistor and the bottom electrode of the ferroelectric capacitor are electrically coupled through a plug layer made of silicon (Si) and also an anti-diffusion layer for preventing diffusion of a chemical element on the bottom electrode of the ferroelectric capacitor is provided. The anti-diffusion layer is for preventing conductivity of the bottom electrode from being lost when silicon is diffused from the plug layer onto the bottom electrode and oxidized in the top layer portion. The anti-diffusion layer is also for preventing a capacitor characteristic from being significantly deteriorated when the silicon is diffused onto the ferroelectric film. Both are caused by thermal annealing at a high temperature of approximately 600-800xc2x0 C. in forming the ferroelectric film. As such a ferroelectric memory, for example, a ferroelectric memory in which the anti-diffusion layer including iridium (Ir), hafnium (Hf), and oxygen (O) is formed in the bottom electrode and the ferroelectric film is composed of layer structure oxide consisting of strontium (Sr), bismuth, tantalum (Ta) and oxygen has been conventionally reported (Refer to Japanese Unexamined Patent Application Publication No. Hei 10-242409.)
However, in the conventional ferroelectric memory, when the common MOS (Metal-Oxide-Semiconductor) type memory structure is employed, hydrogen annealing at a temperature of 400-500xc2x0 C., which is performed for recovering functionality of a transistor before the metal wiring process, deteriorates characteristics of a ferroelectric capacitor. This is considered to be because when precious metal other than platinum or gold (Au) is used for the bottom electrode including the anti-diffusion layer, precious metal oxide which has been produced through thermal annealing at the time of forming the ferroelectric film is reduced by hydrogen annealing and therefore composition or the like of the ferroelectric film significantly changes.
Therefore, it is considered that deterioration of the ferroelectric capacitor can be prevented by performing thermal treatment or the like in a nitrogen gas atmosphere prior to hydrogen annealing. However, a thus manufactured ferroelectric memory has a problem such that adhesion of the bottom electrode weakens.
The present invention has been achieved in view of above problems, and it is an object of the present invention to provide a dielectric capacitor and a memory, in which an electrode has good adhesion, and a method of manufacturing the same.
A dielectric capacitor according to the present invention wherein each of a first electrode and a second electrode is connected to a dielectric film is supported by a substrate portion. The first electrode includes an oxygen inclusion layer, which is provided between the substrate portion and the dielectric film including oxygen, a precious metal layer, which is provided between the oxygen inclusion layer and the substrate portion, including at least one selected from a precious metal element group consisting of platinum, iridium, ruthenium, rhodium and palladium and an adhesive layer provided between the precious metal layer and the substrate portion.
In another dielectric capacitor according to the present invention, each of the first electrode and the second electrode is connected to the dielectric film and at least one of the first electrode and the second electrode comprises a layer including an alloy made of at least one selected from a precious metal element group consisting of platinum, iridium, ruthenium, rhodium and palladium, and at least one selected from a transition metal element group consisting of hafnium, tantalum, zirconium, niobium, vanadium, molybdenum, tungsten and a rare-earth element. The composition formula of the alloy is expressed by MIIIdMIVe, where an element in the precious metal element group is indicated by MIII and an element in the transition metal element group is indicated by MIV, and its composition range is 97xe2x89xa7dxe2x89xa790, 10xe2x89xa7exe2x89xa73, d+e=100 in atom %.
A memory according to the present invention includes a dielectric capacitor which is supported by the substrate portion and in which each of a first electrode and a second electrode is connected to a dielectric film. The first electrode, which is provided between the substrate portion and the dielectric film, comprises a precious metal layer including at least one selected from a precious metal element group consisting of platinum (Pt), iridium (Ir), ruthenium (Ru), rhodium (Rh) and palladium (Pd), which is provided between the oxygen inclusion layer and the substrate portion, and an adhesive layer provided between the precious metal layer and the substrate portion.
Another memory according to the present invention includes a dielectric capacitor in which each of a first electrode and a second electrode is connected to a dielectric film. At least one of the first electrode and the second electrode comprises a layer including an alloy made of at least one selected from a precious metal element group consisting of platinum (Pt), iridium (Ir), ruthenium (Ru), rhodium (Rh) and palladium (Pd), at least one selected from a transition metal element group consisting of hafnium (Hf), tantalum (Ta), zirconium (Zr), niobium (Nb), vanadium (V), molybdenum (Mo), tungsten (W) and a rare-earth element. The composition formula of the alloy is expressed by MIIIdMIVe, where an element in the precious metal element group is MIII and an element in the transition metal element group is MIv and its composition range is 97xe2x89xa7dxe2x89xa790, 10xe2x89xa7exe2x89xa73, d+e=100 in atom %.
A method of manufacturing a dielectric capacitor according to the invention is for manufacturing a dielectric capacitor which is supported by the substrate portion, and in which each of the first electrode and the second electrode is connected to the dielectric film and the first electrode includes an adhesive layer. The step for forming the first electrode in the method of manufacturing a dielectric capacitor according to the invention includes a step of depositing a first layer, which is to construct the adhesive layer, on the substrate portion, a step of depositing a second layer on the first layer, using at least one selected from the precious metal element group consisting of platinum (Pt), iridium (Ir), ruthenium (Ru), rhodium (Rh) and palladium (Pd), and a step of depositing a third layer including oxygen on the second layer.
A method of manufacturing a memory according to the present invention is for manufacturing a memory including a dielectric capacitor which is supported by the substrate portion, and in which each of the first electrode and the second electrode is connected to the dielectric film and the first electrode includes an adhesive layer. The step for forming the first electrode in the method of manufacturing a memory according to the present invention includes a step of depositing a first layer, which is to construct the adhesive layer, on the substrate portion, a step of depositing a second layer on the first layer using at least one selected from the precious metal element group consisting of platinum (Pt), iridium (Ir), ruthenium (Ru), rhodium (Rh) and palladium (Pd), and a step of depositing a third layer including oxygen on the second layer.
A dielectric capacitor according to the present invention includes the adhesive layer including at least one selected from the precious metal element group between the substrate portion and the oxygen inclusion layer, thereby obtaining strong adhesion.
In another dielectric capacitor according to the present invention, at least one of the first electrode and the second electrode is composed so as to comprise a layer including an alloy MIIIdMIve made of at least one selected from the precious metal element group and at least selected one from the transition element group. Thus, strong adhesion is obtained.
A memory according to the present invention comprises the dielectric capacitor of the invention.
In a method of manufacturing a dielectric capacitor according to the invention, the first layer, which is to compose the adhesive layer, is first deposited on the substrate portion, the second layer is then deposited on the first layer using at least one selected from the precious metal element group, and finally the third layer including oxygen is deposited on the second layer.
A method of manufacturing a memory according to the present invention includes steps of the method of manufacturing a dielectric capacitor of the invention.
Other and further objects, features and advantages of the invention will appear more fully from the following description.